Consolidation device and method

ABSTRACT

An apparatus and method for consolidating a composite workpiece are provided. The apparatus includes an electromagnetic field generator for inducing a current and thereby heating a susceptor in thermal communication with the workpiece. The workpiece is supported by one or more support tools, each of which transmits the electromagnetic field so that the support tools are not substantially heated by the electromagnetic field. Thus, the time and energy required for heating the workpiece are reduced relative to conventional consolidation techniques.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The present invention relates to composite materials and, moreparticularly, relates to the consolidation of composite material byinductively heating the material and applying pressure thereto.

2) Description of Related Art

Composite materials typically include a fibrous material such asgraphite that is interspersed in, or impregnated with, a matrixmaterial. The fibrous material is generally strong and stiff and is heldin place by the matrix material, which can be formed of a thermoplasticresin, a thermoset resin, or a metal. In combination, the fiber andmatrix materials can provide a strong, stiff, lightweight material,which can also have dimensionally specific properties. Examples ofcomposite materials include alumina-, boron-, or silicon carbide-basedfibers provided in a weave, braid, or non-woven arrangement and combinedwith a matrix formed of Ultem® resin, a registered trademark of GeneralElectric Company, or a metal such as titanium or aluminum.

Composite materials are consolidated during conventional manufacture byany of a number of methods such as vacuum hot pressing or hot isostaticpressing. These processes typically require long heat cycles due to theheating and cooling required for the tooling that is used to heat andconsolidate the composite materials. The time and energy requirementsresult in high manufacture costs. U.S. Pat. No. 5,229,562 to Burnett, etal. and assigned to the assignee of the present invention, describes amanufacturing method for a composite workpiece in which an electricallyconductive support is used to support the workpiece. The support isinductively heated, and thermal energy is conducted from the support tothe workpiece. The mass and shape of the support can be controlled sothat the workpiece can be heated evenly to a temperature sufficient forconsolidation. However, the energy required to inductively heat thesupport adds to the manufacturing cost of the composite workpiece. Inaddition, temperature changes in the support can cause dimensionalvariations, thereby affecting the finished shape of the workpiece.Further, the time required for cooling the support between consolidationoperations increases the manufacturing time for the workpieces.

Thus, there exists a need for an improved apparatus and method forconsolidating a composite material. The apparatus and method should becapable of heating and cooling the composite material quickly to andfrom a temperature sufficient for consolidation. Preferably, theapparatus and method should not require that large support members areheated and cooled during each cycle.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved apparatus and method forconsolidating a composite workpiece. The workpiece is heated by inducinga current in a susceptor. The current is induced by an electromagneticfield, which is transmitted through one or more support tools thatsupport the workpiece. The electromagnetic field does not inducesignificant electrical current in the support tools, and the supporttools are not substantially heated, thus reducing the energy requiredfor heating the workpiece and reducing the time required for cooling thesupport tools. Further, the workpiece can be heated accurately anduniformly to a processing temperature.

According to one embodiment of the present invention, the apparatusincludes at least two consolidation rollers configured to form a niptherebetween for receiving the workpiece. At least one support tool isconfigured to support the workpiece in the nip, and at least onesusceptor is disposed between the workpiece and the support tool so thatthe susceptor is in thermal communication with the workpiece. Anelectromagnetic field generator, such as an induction coil, isconfigured to generate an electromagnetic field for inducing the currentin the susceptor and heating the susceptor and the workpiece to theprocessing temperature at which the workpiece can be consolidated in thenip. For example, each susceptor can be heated to a Curie temperatureabove which the susceptor becomes paramagnetic. Each support tool can beformed of a plurality of members, such as metal plates, that extend in adirection parallel to a direction of motion of the workpiece through thenip. An insulative material can be provided between the members toprevent electrical conduction therebetween. Actuators rotate the rollersto advance the workpiece and urge the rollers together to consolidatethe workpiece.

According to one aspect of the invention, the support tools are providedas support tracks, which can extend endlessly around the consolidationrollers. Each susceptor can also be provided as an endless sheet. Thus,a continuous workpiece can be advanced through the apparatus andconsolidated. One or more engagement tracks can be provided for engagingthe transverse edges of the susceptors into electrical contact so thatthe current induced in the susceptors flows therebetween. Eachengagement track can include an inflatable bladder.

The present invention also provides a method of consolidating aworkpiece. The method includes providing the support tools in aface-to-face, opposing relationship and disposing at least one susceptorand the workpiece between the support tools. The workpiece can bedisposed as preimpregnated tapes, and the workpiece, susceptor, andsupport tools can be provided as continuous or endless members ortracks. An electromagnetic field is generated to induce an electriccurrent in the susceptors and heat the susceptors and the workpiece to aprocessing temperature. For example, an induction coil can be used toheat the susceptor to its Curie temperature, thereby heating theworkpiece to a processing temperature for consolidation. Theelectromagnetic field is substantially transmitted through the supporttools. The workpiece is consolidated, for example, by advancing theworkpiece, susceptors, and support tools through a nip between rollers.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 is an elevation view illustrating an apparatus for consolidatingcomposite materials, according to one embodiment of the presentinvention;

FIG. 2 is a side view illustrating the right side of the apparatus ofFIG. 1;

FIG. 3 a section view illustrating the apparatus of FIG. 1, as seenalong line 3—3 of FIG. 1;

FIG. 4 is an elevation view illustrating an apparatus for consolidatingcomposite materials, according to another embodiment of the presentinvention; and

FIG. 5 is a section view illustrating the apparatus of FIG. 4, as seenalong line 5—5 of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, this invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

Referring now to the drawings, and in particular to FIGS. 1 and 2, thereis illustrated a consolidation apparatus 10, according to one embodimentof the present invention. The apparatus 10 can be used to consolidate acomposite workpiece 12 by heating the workpiece 12 to a processingtemperature and applying pressure to the workpiece 12. The apparatus 10includes two pairs of consolidation rollers 14, 16 that define two nips18, 20. During operation, the workpiece 12 is disposed between supporttools 22, 24, and the tools 22, 24 and workpiece 12 are then translatedlongitudinally through the nips 18, 20. Induction coils 30 are alsoprovided for heating one or more susceptors 34 disposed between thesupport tools 22, 24, and in thermal communication with the workpiece12.

The term “workpiece” is not mean to be limiting, and it is understoodthat the workpiece 12 can be provided as a layered or otherwisenonuniform structure that includes a fibrous material and a matrixmaterial. A variety of fibrous and matrix materials can be used. Forexample, the fibrous material in the workpiece 12 can be alumina-based,boron-based, carbon-based, or silicon carbide-based fibers. The fiberscan be provided in a weave, braid, or non-woven arrangement. The matrixmaterial can be a resin, such as Ultem® resin, or a metal such astitanium, aluminum, or alloys thereof. The fiber and matrix materialscan be provided separately, for example, as a fibrous mat and a film ofthe matrix material. Alternatively, the fiber and matrix materials canbe provided together, for example, as preimpregnated tapes of the fiberinfused with the matrix material or as a sheet of the matrix materialwith fibers interposed therein. The workpiece 12 can be a sheet thatcorresponds to the dimensions of a particular structural member that isto be formed from the workpiece 12. Alternatively, the workpiece 12 canbe a large, or continuous, sheet from which a number of structuralmembers can be formed. After consolidation, the workpieces 12 can becut, formed, or otherwise processed to manufacture one or morestructural members such as a spar, beam, or panel, which can be used ina variety of applications, for example, as a skin or structural supportin an aircraft wing aircraft fuselage, other aeronautical vehicles,buildings and other structures, and the like. The workpieces 12 can alsobe used to fabricate structural members for a wide variety of otherapplications including, without limitation, structural panels or othermembers for automotive or marine applications or the like. Apparatusesand methods for forming composite materials are provided in U.S.application Ser. No. 10/640,188, entitled “Forming Apparatus andMethod,” filed concurrently herewith, and which is assigned to theassignee of the present invention and is incorporated herein byreference.

Each of the rollers 14, 16 can be connected to a frame 26. As shown inFIG. 1, some of the rollers 16 can be freely rotatable with asubstantially fixed axis, such that the rollers 16 guide the supporttools 22, 24 and workpiece 12 but do not provide a substantialconsolidation force. Other rollers 14 can be adjustably controlled byactuators 28 relative to the workpiece 12 to adjust the nip 18therebetween and provide an adjustable consolidation force on theworkpiece 12. Further, the actuators 28 can be configured to rotate therollers 14, 16, thereby advancing or retracting the support tools 22, 24and workpiece 12 through the apparatus 10. Each roller 14, 16 can beadjusted using a single one of the actuators 28, or separate actuatorscan be provided for rotatably and linearly adjusting the rollers 14.Each of the actuators 28 can be hydraulically, pneumatically,electrically, or otherwise powered. Preferably, the rollers 14, 16 areformed of a material such as steel that is sufficiently strong and stiffso that the rollers 14, 16 can provide a substantially uniformconsolidation force on the workpiece 12.

The workpiece 12 is heated by an electromagnetic field generator such asthe induction coils 30 which can include one or more solenoid coils thatextend around the workpiece 12 and the support tools 22, 24, as shown inFIGS. 2 and 3. Alternatively, each induction coil 30 can be disposedentirely on one side of the workpiece 12, for example, so that first andsecond induction coils 30 are disposed in planes parallel to the planeof the workpiece 12, with the first induction coil 30 on one side of theworkpiece 12 and the second induction coil 30 on an opposite side of theworkpiece 12. Each induction coil 30 typically includes a plurality ofelongate tube sections connected by curved tube sections to form coilsthat are positioned proximate to the workpiece 12 and the susceptor 34in which the current is to be induced. The tube sections can bepositioned uniformly relative to the susceptor 34 so that the susceptor34 is heated substantially uniformly. The tube sections are generallyformed of an electrically conductive material such as copper. Lightlydrawn copper tubing can be used so that the tubing can be adjusted asnecessary to correspond to the configuration of the apparatus. Forexample, the induction coils 30 can be formed of 1.0 inch square coppertubing with a 0.0625 inch wall thickness. Alternatively, tubularsections of other sizes and/or other cross-sectional shapes such asround or triangular tubes can be used.

The induction coil 30 is capable of being energized by one or more powersupplies 32, as shown in FIG. 3. The power supply 32 provides analternating current to the induction coil 30, e.g., between about 3 and10 kHz. This alternating current through the induction coil 30 induces asecondary current within the susceptor 34 that heats the susceptor 34and, thus, the workpiece 12. The temperature of the susceptor 34 and theworkpiece 12 can be inferred by monitoring electrical parameters withinthe one or more power supplies 32, as described in U.S. application Ser.No. 10/094,494, entitled “Induction Heating Process Control,” filed Mar.8, 2002, and U.S. Pat. No. 6,528,771, entitled “System and Method ForControlling an Induction Heating Process,” issued Mar. 4, 2003, each ofwhich is assigned to the assignee of the present invention and isincorporated herein by reference.

The induction coil 30 can also define a passage for circulating acooling fluid from a coolant source 38, for example, a water supply asshown in FIG. 3. A pump (not shown) circulates the cooling fluid fromthe coolant source 38 through the passage. The cooling fluid cools theinduction coil 30 to maintain low electrical resistivity in the coil 30.

Preferably, the induction coils 30 or other electromagnetic fieldgenerator is configured to heat the workpiece 12 without substantiallyheating the support tools 22, 24, thereby reducing the time and energyrequired for heating and cooling. For example, each support tool 22, 24can be substantially transparent to the electromagnetic field generatedby the induction coils 30, and the susceptor 34, which is adapted to beheated by the electromagnetic field, can be provided in thermalcommunication with the workpiece 12. By the term “substantiallytransparent,” it is meant that the support tools 22, 24 are configuredto substantially transmit the electromagnetic field therethrough, i.e.,the electromagnetic field extends through the support tools 22, 24, withlittle or no current being induced in the support tools 22, 24 so thateach support tool 22, 24 is heated only insubstantially or not at all bythe electromagnetic field. Further, the susceptor 34 can have arelatively low thermal capacity so that the susceptor 34 can be quicklyheated to the processing temperature and subsequently cooled, therebyreducing or eliminating the need to cool the support tools 22, 24between operations.

In addition to being substantially transparent to the electromagneticfield, the support tools 22, 24 are also preferably rigid and strong forsupporting and compressing the workpiece 12. According to oneembodiment, the support tools 22, 24 are formed of a plurality oflongitudinal members, which are formed of an electrically conductivematerial but electrically isolated. For example, as shown in FIG. 3,each member 40 is a stainless steel plate that extends the length of therespective support tool 22, 24, about 144 inches in this case, and hascross-sectional dimensions of about 1 inch by ⅛ inch. The members 40 arearranged in a generally parallel configuration such that the members 40extend parallel to the direction of motion of the workpiece 12 throughthe induction coil 30 and the nips 18, 20. The members 40 can be adheredtogether using an adhesive or mechanically constrained using clips,clamps, bolts, or other components. An insulative, or dielectric,material 41 such as aluminum oxide is thermal sprayed on the members 40so that current does not flow between adjacent members 40. Otheroxide-based dielectric coatings can alternatively be used, and thecoatings can be painted, thermal sprayed, or otherwise disposed on themembers 40.

The induction coils 30 can be tuned or otherwise configured to generatean electromagnetic field that is substantially transmitted through theparticular support tools 22, 24 used in the apparatus 10. For example,in one embodiment, the induction coils 30 are configured to generate analternating electromagnetic field at a frequency of about 3 KHz, andeach of the members 40 of the support tools 22, 24 is formed of 300series stainless steel and has at least one cross-sectional dimensionthat is less than about ¼ inch. Although the theoretical explanation ofthis phenomenon is not relied upon as a basis for patentability, it isbelieved that 300 stainless steel has a current depth of about ½ inchunder these conditions and therefore substantially no current is inducedin the members 40. Thus, the induction coils 30 induce a current withinthe susceptor 34 without inducing an appreciable current in the supporttools 22, 24, thereby saving energy and time. Further, by limiting thetemperature variation of the support tools 22, 24, thermally-induceddimensional variations in the support tools 22, 24 can also beminimized.

A faceplate 42 can be provided on the support tools 22, 24 such that thefaceplates 42 are directed toward the workpiece 12 between the supporttools 22, 24. The faceplates 42 can be formed of a material thatexhibits little or no electromagnetic absorption such as ceramic or acomposite material that has a matrix of ceramic and fibrous materialstherein. The ceramic material can be an aluminum silicate binder. Thefaceplates 42 provide a durable liner to the support tools 22, 24 andelectrically isolate the support tools 22, 24 from the workpiece 12 andsusceptor 34.

The susceptor 34 can be provided as one or more thin sheets or foilsthat extend around the workpiece 12, as shown in FIG. 3. For example, asshown in FIGS. 2 and 3, the susceptor 34 can be disposed as sheets 34 a,34 b on opposing surfaces of the workpiece 12, and the edges 36 of thesheets 34 a, 34 b can be engaged so that the workpiece 12 is containedwithin the susceptor 34. For example, the edges 36 of the sheets 34 a,34 b can be bent about the edges of the workpiece 12 and engaged bypressing, crimping, welding, or otherwise electrically engaging thesheets 34 a, 34 b. Alternatively, a single susceptor can be wrappedaround the workpiece 12, or otherwise disposed thereon, so that thesusceptor(s) extend around the workpiece 12. The susceptor 34 can alsobe coated, for example, with an oxidation resistant nickel aluminidecoating that can be flame-sprayed or otherwise disposed on the surfacethereof. A description of a susceptor with a nickel aluminide coating isprovided in U.S. application Ser. No. 10/032,625, entitled “SmartSusceptors with Oxidation Control,” filed Oct. 24, 2001, and which isassigned to the assignee of the present invention and is incorporatedherein by reference. The susceptor 34 can also be coated with a releaseagent that facilitates the removal of the workpiece 12 afterconsolidation.

Further, the susceptor 34 can be formed of a material that ischaracterized by a Curie temperature at which the susceptor 34 becomesparamagnetic, for example, a ferromagnetic alloy such as an alloy ofiron and nickel. One such alloy, generally referred to as Kovar®, aregistered trademark of CRS Holdings, Inc., includes approximately 53%iron, 29% nickel, 17% cobalt, and 0.2% chromium. Susceptors having Curietemperatures at which each susceptor becomes non-magnetic, orparamagnetic, are described in U.S. Pat. No. 5,728,309, entitled “Methodfor Achieving Thermal Uniformity in Induction Processing of OrganicMatrix Composites or Metals,” which issued on Mar. 17, 1998; U.S. Pat.No. 5,645,744, entitled “Retort for Achieving Thermal Uniformity inInduction Processing of Organic Matrix Composites or Metals,” whichissued on Jul. 8, 1997; and U.S. Pat. No. 5,808,281, entitled“Multilayer Susceptors for Achieving Thermal Uniformity in InductionProcessing of Organic Matrix Composites or Metals,” which issued on Sep.15, 1998, each of which is assigned to the assignee of the presentinvention and is incorporated herein by reference.

Thus, the susceptor 34 extends around the workpiece 12, and eddycurrents can be induced in the susceptor 34 by the induction coils 30.Eddy current heating of the susceptor 34 results from eddy currents thatare induced in the susceptor 34 by the electromagnetic field generatedby the induction coil 30. The flow of the eddy currents through thesusceptor 34 results in resistive heating of the susceptor 34. Accordingto one embodiment of the present invention, the susceptor 34 is heatedby the eddy current heating to the Curie temperature of the susceptor34, whereupon the susceptor 34 becomes paramagnetic and does not heatfurther. If some portions of the susceptor 34 are heated more quicklythan other portions, the hotter portions will reach the Curietemperature and become paramagnetic before the other, cooler portions ofthe susceptor 34. The eddy currents will then flow through the coolermagnetic portions, i.e., around the hotter, paramagnetic portions of thesusceptor 34, causing the cooler portions to also become heated to theCurie temperature. Therefore, even if some portions of the susceptor 34heat at different rates, the entire width of the susceptor 34 and,therefore, the workpiece 12, is heated to a uniform Curie temperature asthe workpiece 12 passes by or through the induction coil 30. Thesusceptor 34 can also act as a magnetic shield that prevents theinduction coil 30 from inducing a current in the workpiece 12. Further,in some cases, the workpiece 12 is formed of electrically nonconductivematerials that are not receptive to an induced current. As such, theinduction coil 30 does not heat the workpiece 12 directly, but ratherheats the susceptor 34, which, in turn, heats the workpiece 12.

The Curie temperature of the susceptor 34 can correspond to theprocessing temperature of the workpiece 12, i.e., the temperature atwhich the workpiece 12 can be consolidated. For example, the Curietemperature of the susceptor 34 can be equal to the processingtemperature or slightly greater than the processing temperature so thatthe workpiece 12 is heated to the processing temperature when thesusceptor 34 is heated to the Curie temperature. The processingtemperature of the workpiece 12 can be equal to the melting temperatureof the matrix material or otherwise sufficiently high that the workpiece12 can be consolidated at the processing temperature. Thus, thesusceptor 34 can be used to heat the workpiece 12 uniformly to theprocessing temperature so that the workpiece 12 can be consolidated bythe pressure applied by the rollers 14. The susceptor 34 can be formedof a variety of materials, and the composition of the susceptor 34 canbe designed to achieve a desired Curie temperature that corresponds tothe processing temperature of a particular type of composite material.For example, in one embodiment, the susceptor 34 is formed of Kovar®,which has a Curie temperature of about 750° F., at which temperatureUltem® resin can be melted and consolidated with fibrous materials suchas graphite to form a composite structure.

The workpiece 12 can be heated by the induction coil 30 to theprocessing temperature and consolidated by the rollers 14contemporaneously with or shortly after heating. For example, theinduction coils 30 can be situated relative to the rollers 14 such thatthe workpiece 12 is advanced from the induction coils 30 to the rollers14, i.e., toward the right as shown in FIG. 1. Due to the stiffness ofthe support tools 22, 24, the rollers 14 apply pressure to consolidatethe workpiece 12 over an area that is greater than the area of contactbetween the rollers 14 and the support tools 22, 24. According to oneembodiment, the susceptor 34 has a low thermal capacity so that thesusceptor 34 and workpiece 12 are at least partially cooled while beingconsolidated by the roller 14.

According to another embodiment of the present invention illustrated inFIGS. 4 and 5, the apparatus 10 can be used to continuously consolidatea composite workpiece 12, i.e., the composite workpiece 12 can beprovided continuously during operation of the apparatus 10 and theworkpiece 12 can have any length. The workpiece 12 can be formed of aplurality of preimpregnated tapes 44 that are dispensed from rolls 46.As is known in the art, preimpregnated tapes are strips of compositematerial that include fibers impregnated with a matrix material. Anynumber of tapes 44 can be disposed continuously between first and secondsupport tracks 48, 50 to form the desired thickness and width of theworkpiece 12 therebetween. Alternatively, the rolls 46 can be continuoussheets of fibrous and matrix materials that are layered and used for acombination resin-infusion and consolidation process in the apparatus10. For example, multiple carbon fiber mats can be layered alternatelywith sheets of resin film so that the apparatus 10 melts the resin,infuses the resin in the carbon mats, and consolidates the resultingcomposite workpiece 12.

The support tracks 48, 50 can be formed of links 52 that are rotatablyconnected to form an endless track. Each link 52 can be similar to oneof the support tools 22, 24 described above, including multipleelectrically isolated members 40. Adjacent links 52 are hinged orotherwise rotatably connected such that the adjacent links 52 can berotated or articulated at least in one direction. The tracks 48, 50 aresupported by track guides 54, which can be rotatable rollers that guidethe tracks 48, 50. The guides 54 can be mounted to the frame 26 and canalso maintain tension in the tracks 48, 50.

As also shown in FIG. 4, the susceptor 34 can be provided as first andsecond susceptor sheets 60, 62 that are passed continuously through thenips 18, 20 of the apparatus 10. The susceptor sheets 60, 62 can beendless loops, as shown, and can be supported by susceptor loop guides64 that guide the susceptor sheets 60, 62 through the apparatus 10. Eachsusceptor sheet 60, 62 can extend around a respective one of the supporttracks 48, 50 so that the susceptor sheet 60, 62 extends between thetracks 48, 50 in the nips 18, 20. Similar to the track guides 54, thesusceptor guides 64 can be mounted to the frame 26 and can maintaintension in the susceptor sheets 60, 62.

Additionally, continuous susceptor engagement tracks 70, 72 can beprovided for one or both of the susceptor sheets 60, 62. The susceptorengagement tracks 70, 72 can be provided on both sides of the workpiece12 and can be guided by track guides 74, such as rotatable rollerssimilar to the guides 54, 64. Each engagement track 70, 72 can be formedof a plurality of articulated links 76, for example, with hingeconnections therebetween, and the engagement tracks 70, 72 can beendless. As shown in FIG. 5, the engagement tracks 70, 72 can bereceived in the nips 18, 20 between the rollers 14, 16 so that theengagement tracks 70, 72 are urged together between the rollers 14 andpress the edges 66 of the susceptor sheets 60, 62 together. The links 76can be formed of a variety of materials including metals such as copper,and the links 76 can be stiff so that the links 76 exert a substantiallyuniform pressure on the edges 66 of the susceptor sheets 60, 62 over thelength of the links 76. Some or all of the engagement tracks 70, 72 canalso include an inflatable bladder 78 that is fluidly connected to apressurized fluid source (not shown) for pressurizing and expanding thebladder 78 to maintain a compressive force on the edges 66 of thesusceptor sheets 60, 62. Preferably, the bladders 78 are formed of apliable material that can withstand the temperatures associated withconsolidating the workpiece 12. The fluid source can be a pressuregeneration device, such as a compressor, or the source can be a pressurevessel that contains the pressurized fluid such as air, argon, or otherinert gases. The fluid source can include a pressure regulation devicein fluid communication with each of the bladders 78 and configured tomaintain a substantially equal pressure in each bladder 78. Further, acooling fluid can be circulated through the bladders 78, through otherpassages in the links 76, or otherwise in contact with the links 76 tocool the links 76. Other mechanisms can alternatively be provided forurging the edges 66 of the susceptor sheets 60, 62 into electricalcontact.

The operations for consolidating a workpiece 12 according to oneembodiment of the present invention will now be described. It isunderstood that one or more of the operations can be omitted accordingto other embodiments of the present invention. The method includesproviding the support tools 22, 24 in a face-to-face, opposingrelationship and disposing at least one susceptor 34 and the workpiece12 between the support tools 22, 24. The workpiece 12 can be disposed,for example, as a plurality of continuous preimpregnated tapes, orfibrous mats and resin films, that are disposed between two continuouslayers 60, 62 of the susceptor 34. Additionally, the support tools 22,24 can be provided as continuous or endless members or tracks 48, 50.Thus, the workpiece 12 and susceptors 60, 62 can be disposed between thesupport tracks 48, 50, which are passed continuously through the nips18, 20. Bladders 78 in communication with the transverse edges 66 of thesusceptors 60, 62 are inflated to urge the edges 66 into electricalcontact. An electromagnetic field is generated to induce an electriccurrent in the susceptors 60, 62 and heat the susceptors 60, 62 and theworkpiece 12 to a processing temperature. For example, an induction coil30 can be energized to generate the electromagnetic field and heat thesusceptors 60, 62 to the Curie temperature, above which the susceptors60, 62 becomes paramagnetic. Preferably, the electromagnetic field issubstantially transmitted through the support tracks 60, 62. Theworkpiece 12, susceptors 60, 62, and support tracks 60, 62 are advancedthrough the nip 18 between the rollers 14 so that the workpiece 12 isconsolidated.

Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

1. A method of consolidating a workpiece, the method comprising:providing first and second support tools in a face-to-face, opposingrelationship; disposing at least one susceptor and workpiece between thesupport tools; generating an electromagnetic field, thereby inducing anelectric current in the susceptors and heating the susceptors and theworkpiece to a processing temperature, the support tools beingsubstantially transparent to the electromagnetic field such that theelectromagnetic field is substantially transmitted through the supporttools; and advancing the workpiece, susceptors, and support toolsthrough a nip and thereby consolidating the workpiece.
 2. A methodaccording to claim 1 wherein said providing step comprises providingfirst and second support tracks having rotatable links.
 3. A methodaccording to claim 1 wherein said disposing step comprises disposing aworkpiece between opposed layers of the susceptor.
 4. A method accordingto claim 1 wherein said disposing step comprises disposing a pluralityof preimpregnated tapes to form thin workpiece.
 5. A method according toclaim 1 wherein said disposing step comprises disposing a plurality oflayered fibrous mats and resin films to form the workpiece.
 6. A methodaccording to claim 1 wherein said disposing step comprises disposing acontinuous workpiece.
 7. A method according to claim 1 wherein saiddisposing step comprises disposing at least one continuous susceptor. 8.A method according to claim 1 wherein said generating step comprisesheating the susceptor to a Curie temperature above which the susceptorbecomes paramagnetic, the Curie temperature corresponding to theprocessing temperature of the workpiece.
 9. A method according to claim1 wherein said generating step comprises energizing an induction coilextending proximate to the workpiece and the susceptor to generate theelectromagnetic field.
 10. A method according to claim 1 wherein saidconsolidating step comprises advancing the workpiece, susceptors, andsupport tools through a nip formed between at least two rollers.
 11. Amethod according to claim 1 further comprising engaging at least twotransverse edges of the susceptor into electrical contact at a locationproximate to the electromagnetic field generator such that a currentinduced in the susceptors by the electromagnetic field generator flowsbetween the susceptors.
 12. A method according to claim 11 furthercomprising inflating a bladder in communication with the transverseedges to urge the edges together.
 13. A method according to claim 1wherein said disposing step comprises disposing continuous supporttools.
 14. A method of consolidating a workpiece, the method comprising:providing first and second support tools in a face-to-face, opposingrelationship as first and second support tracks having rotatable links;disposing at least one susceptor and workpiece between the supporttools; generating an electromagnetic field, thereby inducing an electriccurrent in the susceptors and heating the susceptors and the workpieceto a processing temperature, the support tools being substantiallytransparent to the electromagnetic field such that the electromagneticfield is substantially transmitted through the support tools; andconsolidating the workpiece.
 15. A method of consolidating a workpiece,the method comprising: providing first and second support tools in aface-to-face, opposing relationship; disposing at least one susceptorand workpiece between the support tools; engaging at least twotransverse edges of the susceptor into electrical contact at a locationproximate to the electromagnetic field generator such that a currentinduced in the susceptors by the electromagnetic field generator flowsbetween the susceptors, thereby inflating a bladder in communicationwith the transverse edges to urge the edges together; generating anelectromagnetic field, thereby inducing an electric current in thesusceptors and heating the susceptors and the workpiece to a processingtemperature, the support tools being substantially transparent to theelectromagnetic field such that the electromagnetic field issubstantially transmitted through the support tools; and consolidatingthe workpiece.